American Elm Ulmus americana Ulmaceae—Elm family by Tom Reaume © 2010 Nature Manitoba deciduous, long-lived, shade tree 10–35 m tall with a spreading crown 10–28 m wide from thick, grace- ful branches; solitary or in groups, often planted in Acities and towns for shade and wildlife; along rivers and streams, fence rows and fields; on well drained soils. l FLOWERS reddish green, blooming February–May before the leaves appear; inflorescences numerous, of small, 1–6 fascicles of flowers along the new twigs formed last year; pedicels green, unequal, 3–25 mm long by c. 0.3 mm thick with flower, round, glabrous, ascending, with a joint in the upper half; bracteoles one or two at base of pedicels, erect, light reddish brown, 2–5 mm long includ- ing the erect apical hairs; fertile scales of buds, several, Mature American Elms line the streets in the Wolseley reddish brown, C-shaped, 7–9 mm long, somewhat per- district of Winnipeg, Manitoba; late summer sistent, with 3–5 flowers beneath each; flowers perfect, 7–25 flowers per floral bud; calyx cups tubular, angled, 2–3 mm long by 2–4 mm wide, slightly wrinkled, green turning reddish brown, 5- to 9-lobed, the lobes c. 1 mm tall with a few curled white hairs along the flat to notched apices; petals absent; stamens 5–9 (often 6), one per calyx lobe, exserted; filaments pale green, erect, 3–4 mm long, glabrous; anthers dark purplish brown, about 1 mm long and wide, each side with a full length suture; pollen round, whitish green; pistil one, greenish, c. 2 mm long by 1.5 mm wide with whitish ascending marginal hairs; ovary one, flat, shiny; stigmas 2, ascending and arched outward, covered with short numerous whitish hairs, in- cluded in calyx cup but visible at its apex, elongating and exserted as fruit expands. l FRUIT a samara, 1-seeded, thousands per tree, green when young, creamy-tan when ripe, some tinged with reddish purple, thin, winged, 9–16 mm long by 7–10 mm wide by 1–2 mm thick, flattened, heavily veined, the api- cal notch 3–4 mm deep, the twin, pointed apices curved Mature American Elms on a frosty winter’s morning inward, hairs c. 1 mm long, white, along the margins of wings; seed 3.5–4 mm long by 2.3–2.8 mm wide by c. 0.8 mm thick, dull, green ripening to tan, a narrow wing or ridge along one side, base flat, apex somewhat pointed. l LEAVES alternate, simple, margins doubly toothed, dark green turning yellowish in fall; blades 3–15 cm long by 1.3–8 cm wide, pointed, base unequal, 3–11 per new green twig; petioles 2–10 mm long, green, glabrous to slightly hairy, stipules tan, hairy, deciduous, linear, 5–15 mm long by 2.5–6 mm wide, hyaline margins cottony hairy; blades eaten by cankerworms in Winnipeg. l TRUNK erect, branched, round; bark medium gray, with long furrows 1–4 cm deep between the flattish 2–4 cm wide ridges on mature trees; young twigs greenish, turn- ing brown, lightly hairy to glabrous, 3–15 cm long, grayish with age; floral buds large, alternate, 5–9 mm long by 3–4 mm wide by 2–3 mm thick, with several fertile scales, these often with white marginal hairs, some appressed hairs on the scale’s body; leaf buds narrow, alternate, pointed, distal, expanding to c. 2 cm long before opening as the green fruit ripens; lenticels golden tan on twigs. l RANGE: (CAN) 7 provinces; (USA) 40 states; an east- A mature, majestic American Elm in Assiniboine Park; ern soft hardwood tree; the state tree of North Dakota. trunk diameter 75 cm, canopy 26 m wide ripening fruit old twig ridge expanding leaf Leaves begin to appear as the winged fruit 8–10 mm wide is starting to ripen in Winnipeg, Manitoba midrib tip of leaf blade Long vertical flat ridges and furrows (1–4 cm tooth raised side vein deep) define the bark on a 100-year-old American Elm with 80 cm wide trunk; inset 12 cm wide trunk Tip and margin of dorsal (under) side of leaf. Large veins to the right are about 5 mm apart. Large teeth have a smaller or second- ary tooth about half way (doubly toothed) green fruit anther expanding calyx lobe pedicel calyx joint stigma cup pedicel ovary calyx cup calyx cup Pistil x10; hairy subtending spreading stigmas fruit ripening anther bract suture Perfect flower x5; 7 stamens Enlarging green fruit, 5–7 mm long starting to pro- trude from the reddish brown calyx cups. filament Young fruit x8, developing, exserted past calyx cup Stamen x10 leaf blade toothed margin old twig leaf buds ripening fruit New vegetative leaf buds expanding; terminal bud 2 cm long in April; each green fruit 8–10 mm long flowers old twig new twig old twig New leafy green shoot; total length 17 cm, with 6 alternate leaves which developed from a distal leaf bud after the floral buds opened American Elm clusters of flowers in bloom; width of twig with flowers 5 cm apical notch wing or wing ridge seed outline base side thick calyx Seed x7 cup pedicel pointed tip Ripe fruit x5; bud side view scale floral bud wing Terminal leaf calyx stamen bud x7 cup spent Ventral side of an American Elm Growing fruit x5; leaf 8 cm wide in the fall. stamens spent; side Alternate winter buds (floral and leaf) 5–10 mm long along view hairy twig from last year; Winnipeg, Manitoba.
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